Before antibiotics became widely available in the 1940s, a major cause of death was bacterial infectious disease. This has changed with the availability of antibiotics but bacterial organisms have developed resistance mechanisms faster than the development of new antibiotics. The financial and health costs related to antibiotic resistance are enormous and the consequences of reverting to a pre-antibiotic era are dire.
A high percentage of bacteria that cause bloodstream or lung infections in hospitals have developed resistance to at least one antimicrobial drug. The US and global healthcare systems are now regularly encountering multi-drug resistant (MDR) organisms resistant to most or all known antibiotics. According to a 2008 study, at least 25,000 patients in the European Union die from an infection caused by MDR bacteria and estimated additional health-care costs and productivity losses are at least €1.5 billion. In the US, 2 million patients develop MDR health-care associated infections each year and 99,000 die as a result. Direct expenses alone cost between $21 and $34 billion and resistant infections in the US require more than 8 million additional days in the hospital compared to non-resistant infections.
Of particular concern are infections caused by MDR Staphylococcus, including Staphylococcus aureus (S. aureus). While staphylococci can be in 20-30% of healthy adults and in the majority of instances, do not cause disease, damage to the skin or other injury may allow the bacteria to overcome the natural protective mechanisms of the body, leading to infection. Common staphylococcal infections include skin infections, pneumonia, food poisoning, toxic shock syndrome, and blood stream infection (bacteremia).
Methicillin-resistant S. aureus (MRSA) infections began to appear in the US in the 1960s, with vancomycin-resistant strains first reported in 2002. Today, the World Health Organization reports that 95% of S. aureus infections worldwide are resistant to penicillin and 90% are MRSA.
There are more than 180 antibiotics on the market in the US. A comprehensive study of antibiotic development found that in 2008, only 15 antibiotics of 167 under development had a new mechanism of action with the potential to meet the challenge of MDR. Accordingly, an urgent need exists for the development of new antibiotics that are effective against organisms that are resistant to currently-available antibiotics.